Some vehicles such as automobiles are known to be equipped with a parking assist device. The parking assist device assists the vehicle when the vehicle is pulled into a certain parking space and pulled out of the parking space. To pull a vehicle into or out of a parking space, the parking assist device operates the steerable wheels of the vehicle through automatic control of the steering device, instead of using steering operation by the driver. Through the automatic control of the steering device, the steerable wheels are operated to pull the vehicle into or out of the parking space without steering operation by the driver. In this manner, the vehicle is assisted to be pulled into or out of the parking space.
When a vehicle is assisted to be pulled into or out of a parking space by a parking assist device, the steerable wheels are operated solely by the power of the actuator, such as a motor, of the steering device through the automatic control without depending on any steering operation by the driver. This increases the load acting on the steering device when the automatic control is performed compared to usual times. The temperature of the steering device thus tends to increase. In this regard, Patent Document 1 describes a configuration in which automatic control is prohibited if the temperature of the steering device is higher than the maximum value of a first temperature range. As a result, even if the temperature of the steering device increases after the automatic control is started, the temperature of the steering device is maintained at a sufficiently low value.